Laboratory intercomparison of ozone and nitrogen dioxide spectral intensities in the visible and infrared using SCISAT-1

Laboratory absorption spectra of ozone (O3) and nitrogen dioxide (NO2) were measured using SCISAT-1's MAESTRO (Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) and ACE-FTS (Atmospheric Chemistry Experiment-Fourier Transform Spectrometer) spectrometers. A novel solar simulator source was designed and constructed for these measurements. This apparatus allowed for simultaneous measurements of visible and infrared absorption spectra from a common gas cell to be taken. The analysis of these spectra allowed for a direct intercomparison between the visible cross-section data reported in the literature and the infrared line intensities compiled in the HITRAN database. For ozone, results reported here show that Chappuis band cross-section strengths are more consistent with the HITRAN 2004 4.8 mum band line strengths than with the ones reported in the HITRAN 2000 compilation. For nitrogen dioxide, results obtained using three different sets of visible cross-section data show that the Vandaele et al. temperature-dependent cross-sections from 2002 are the most consistent with the HITRAN 2004 line strengths. As well, the pressure-broadened half-width of NO2 by NO is reported, and the thermodynamic equilibrium balance of NO2 with N2O4 has been measured. The results from this work have implications for a number of satellite missions that measure ozone and nitrogen dioxide. An increased certainty in the spectral parameters implies that discrepancies in amounts retrieved by different instruments must be due to other inaccuracies.